Abstract: For long-distance HVDC (High Voltage Direct Current) transmission lines, when the distance from the fault point to two ends is significantly different, the transmission dispersion will cause the traveling wave peak to be smooth and shift. It will lead to additional initial traveling wave moment errors and reduce fault location accuracy. To solve the problem, a dispersion compensation and fault location method for HVDC transmission lines based on nonlinear system identification is proposed. The impulse response of the entire line and segmented lines can be obtained based on actual fault data and short-circuit test data. The adaptive Volterra filter is used to identify the transmission characteristics of the line. The signal's waveform is reconstructed through deconvoluted inversion, which makes the wave peak shift at both ends consistent. The transmission dispersion is compensated, and the fault location accuracy for HVDC lines is improved. The method is verified through simulation and actual data.